1. Field of the Invention
This invention relates to an electrostatic micro-actuator in which the motion of a movable element is remarkably stabilized by sealing a high viscosity fluid between two electroded fixed members, the high-viscosity fluid surrounding a movable element.
2. Description of the Prior Art
Electronic/electrical devices using static electricity as driving force have hardly been developed so far. For, the energy density is incomparably low in comparison with electronic/electrical devices using electromagnetism.
It has been found recently that this drawback can be compensated by miniaturizing the device itself to a micro-size. Accordingly, attempts have now been made to utilize static electricity as the driving source of a micro-actuator. However, means for achieving the stability in a system is necessary because the system utilizing static electricity essentially involves unstability of motion according to the Earnshaw's theorem.
Various methods have been proposed so as to stabilize the system against the Coulomb force acting in the direction perpendicular to the direction of the movement of the movable element inside an electrostatic micro-actuator.
By one of them, for example, mechanical bearings are provided. However, feasibility as well as reliability of this method drop with miniaturization of the size of the system. There is another method using magnetic levitation but the magnetic force itself is not an effective force in a micro-range. In this point, a method utilizing the Meissner effect of a super-conducting material can be an essentially useful means but the problem of the high cost of production brings up because liquid helium or liquid nitrogen, must be prepared. Still another method utilizes ultrasonic wave levitation. However, since the wavelength is in the order of several millimeters, there is a limitation to miniaturization of the system to the micro-size.